In recent years, a technique of using a laser light source for supplying a laser beam in a light source device of a projector, which is an image display apparatus, has been suggested. As compared with an ultra-high pressure mercury lamp (UHP lamp) that has been used as a light source device of a projector, the light source device that uses a laser light source is advantageous in high color reproducibility, instant lighting, a long life, and the like. For example, a technique of using laser light sources for red (R), green (G), and blue (B) colors is proposed in international patent publication WO 04/109390.
As light source devices that use laser light sources, a light source device that directly supplies a fundamental laser from a laser light source and a light source device that converts the wavelength of a fundamental laser and supplies the converted laser are known. As a wavelength conversion element that converts the wavelength of a fundamental laser, for example, a second-harmonic generation (SHG) element is known. In order to display a bright image, a laser light source having a high output may be used in a projector. While a high output can be obtained by direct emission of a laser light source in the case of R light, typically the SHG elements are used to obtain a high output in the case of G light and B light. By using the SHG element, it becomes possible to supply a laser beam having a desired wavelength using a general-purpose laser light source that is easily available. In addition, a configuration in which a sufficient amount of laser beams can be supplied may also be realized.
In the case of the SHG element, a phase matching condition is not effective when the refractive index distribution changes due to a temperature change, and as a result, the wavelength conversion efficiency decreases. In order to supply a stable amount of laser beams with high efficiency, a temperature control of the SHG element is required. In the case of R light that is directly emitted, a time for temperature control of the SHG element is not necessary. However, G light and B light, which are emitted using the SHG element, cannot be emitted until a time required for temperature control after starting passes. If there is a difference in time required for emitting laser beams having desired wavelengths, it is difficult to obtain an image having suitable color balance until a predetermined time passes from starting of the projector. Display of an image having unsuitable color balance until a predetermined time passes tends to create an unfavorable and unpleasant viewing experience for the viewer.